This invention advances the design and performance of miniboats, first described in my U.S. Pat. No. 4,090,270; and it improves and extends their applicability to new areas not previously discussed in connection therewith. The nearest related art, containing nothing having the character of miniboats, encompasses life rafts of many styles and sizes, the larger of which are often very useful. However, as the designed-in seating capacity and bouyancy are reduced, so is the protection afforded the occupant of a one-man raft, whose body and center-of-gravity heights remain undiminished, so that he now towers precariously over a tiny platform that cannot be ballasted by human occupancy. The inevitable consequence of this loss of stability and seakeeping capability in rough water is that the occupant becomes a virtually free body, subject to being thrown about, washed out, and thrown out, often being ejected even by the downwash of a rescue helicopter, which keeps pushing the raft (but not the miniboat) out of rescue reach, and forcing his reimmersion.
Boarding a one-man life raft from the water requires a strong, vaulting, upward plunge out of the water to get over the taut hull, which often responds by tilting so that the would-be boarder must slide back to try again and again. Often boarding cannot be accomplished in cold water without the higher-pressure fill that the inflation gas delivers best when the water is warm, because the hull buckles and tilts, rejecting occupants who would otherwise have enough strength to occupy it. Leakage of oil from a damaged vessel not only inflames the eyes so severely as to disorient survivors in the water but also makes it extremely difficult and often impossible to board a raft because of the consequent slipperiness of the skin, the raft surfaces, and wet, oily clothing. Injured and shocked personnel may be unable to board any raft without help, which is unavailable to parachutists and other lone individuals; and cold-water fatigue will soon rob them of whatever faculties they might otherwise retain.
Growing concern regarding immersion hypothermia spurred makeshift raft add-ons such as inflated floors and cushions, which made the rafts even less stable in open water, and tent-like canopies draped over the occupants' heads, some inflated, which aggravated instability in wind and added so much bulk that the redesigned rafts could no longer be accommodated in the aircraft for which their development had been scheduled.
Though the patented miniboat required much less fabric area than did a raft, weighed less, and needed only oral inflation or a tiny, disposable 2-oz or 56 gram-capacity CO.sub.2 cartridge (vs a mandatory 8-oz or 224 gram requirement for the raft) for primary inflation before boarding, supplemented by oral inflation thereafter, the miniboat revealed none of the above-noted deficiencies of small life rafts. The patented miniboat proved itself to be the quickest and easiest of all flotation devices for a swimming survivor to use unassisted. In fact, swimmers could board it more readily than they could don so-called "life preservers". Open-sea testing overcame initial skepticism; and the Navy has set up several programs for issue of miniboats to its aviators. The presence of oil, though still a hindrance to coordinated effort in the water, will scarcely impede sliding or rolling into a miniboat; and the miniboat, unlike a raft, can then be effectively paddled by hand away from the dangerous surface pool.
Nevertheless, the value of the patent remains limited in that it was focussed upon vehicles that were to be boarded by persons already in the water, who remain thereafter susceptible, especially in colder seasons and latitudes, to severe exposure hypothermia by reason of their prior immersion and body heat loss through their drenched clothing. Even the slow evaporation of the water they bring with them adds to the thermal load upon their weakened vitality.
Should a would-be occupant desire to enter the patented miniboat from a shallow beach, he will find his own weight pinning the hull down on the sand; and he will abrade its thin skin if he tries to slide himself out into the water. If he wades out to boarding depth he becomes partly wet and brings in water. Moreover, if the would-be occupant tries to step from a low pier, it still remains almost impossible to get inside with a dry skin because it lies lightly on one side or other for ease of boarding by a swimmer only; its very lightness, lack of inherent balance and susceptibility to wind when unoccupied become the means by which it eludes personnel transfer from above, unless it has been ballasted, ironically, with a partial water fill. If a would-be occupant should stand or sit within to jump or be thrown from a pier or other structure into the water, he is likely to find it stripped away from him upon impact with the water's surface.
While dry water entry from other media may not be impossible, those who attempt it unaided do so at risk of a thorough wetting. In short, the patented miniboat derived its outstanding character as a vessel solely from the occupant, after he had achieved a position within it, an easy task only for one who is either already immersed in the water or unafraid of a wetting.
Although the severity of wave action that will cause flow over the gunwales of the patented miniboat is much higher than that required for flooding small rafts, whose low-lying tubular hulls are a poor defense, water can still accumulate in the bottom. Precipitation, spray and wind chill are also inducers of hypothermia.